Generate rules.mk for enumn via cargo_embargo

Update cargo_embargo.json to also generate Trusty rules.mk for use
in the Trusty kernel. Running cargo_embargo generate cargo_embargo.json
also made a non-functional change to Android.bp.

Test: cargo_embargo generate cargo_embargo.json
Change-Id: I95306bffe1b6a5f45dd49d8c8d9fedb142905e7b
diff --git a/crates/enumn/cargo_embargo.json b/crates/enumn/cargo_embargo.json
index fbb9fcd..84972c8 100644
--- a/crates/enumn/cargo_embargo.json
+++ b/crates/enumn/cargo_embargo.json
@@ -3,5 +3,6 @@
     "//apex_available:platform",
     "com.android.virt"
   ],
-  "run_cargo": false
+  "run_cargo": false,
+  "generate_rulesmk": true
 }
diff --git a/crates/enumn/rules.mk b/crates/enumn/rules.mk
index e6bee36..db7466d 100644
--- a/crates/enumn/rules.mk
+++ b/crates/enumn/rules.mk
@@ -1,17 +1,17 @@
-# This file is generated by cargo2rulesmk.py --run --features .
-# Do not modify this file as changes will be overridden on upgrade.
+# This file is generated by cargo_embargo.
+# Do not modify this file after the LOCAL_DIR line
+# because the changes will be overridden on upgrade.
+# Content before the first line starting with LOCAL_DIR is preserved.
 
 LOCAL_DIR := $(GET_LOCAL_DIR)
 MODULE := $(LOCAL_DIR)
 MODULE_CRATE_NAME := enumn
 MODULE_RUST_CRATE_TYPES := proc-macro
-MODULE_SRCS := \
-	$(LOCAL_DIR)/src/lib.rs \
-
+MODULE_SRCS := $(LOCAL_DIR)/src/lib.rs
 MODULE_RUST_EDITION := 2018
 MODULE_LIBRARY_DEPS := \
-	external/rust/crates/proc-macro2 \
-	external/rust/crates/quote \
-	external/rust/crates/syn \
+	$(call FIND_CRATE,proc-macro2) \
+	$(call FIND_CRATE,quote) \
+	$(call FIND_CRATE,syn)
 
 include make/library.mk